Over its 100 year history GCHQ has had a presence in London. For the past 66 years GCHQ have been operating from a secret location tucked away on a busy street in Westminster opposite St James' Park tube station. For the first time, GCHQ are able to reveal the role their Palmer Street office has played in keeping the capital and the country safe.

Today's revelation is possible as GCHQ, whilst maintaining a London presence, will no longer operate from the building. It comes as they look to further extend our network of sites in the UK, with a new secure facility in Manchester that opened in 2019.

As well as its headquarters in Cheltenham, GCHQ also has offices in Bude in Cornwall, Scarborough, Lincolnshire and Harrogate. In 2017, the National Cyber Security Centre (NCSC), which is part of GCHQ, opened its new headquarters near Victoria in London.

And earlier this year, Her Majesty the Queen, commemorated GCHQ's 100-year anniversary by unveiling an historic plaque at a different London site - Watergate House, the first home and birthplace of the organisation.

GCHQ, or the Government Code & Cypher School (GC&CS) as it was known at the time, was established on 1 November 1919 as a peacetime cryptanalytic unit made up from staff from the Admiralty's Room 40 and the War Office's MI1.

During WWII, GCHQ staff moved to Bletchley Park where they decrypted German messages, most famously by breaking Enigma-encrypted communications, making a significant contribution to the Allied victory.

In the early 1950s, GCHQ moved its headquarters from the London suburbs of Eastcote to Cheltenham, meaning a suitable central London location was needed for the handling of secret paperwork and as a regular base for the Director. After a substantial search, the Ministry of Works provided a newly-built, Government leased building on Palmer Street. GCHQ moved into their new, secret London home in Spring 1953, housing a range of different teams there over the following decades.

The Palmer Street hub has played its part in significant events over the years, such as the 2012 London Olympics, working with our partners, MI6, MI5 and the Metropolitan Police to counter terrorist activities and serious and organised crime whilst keeping Ministers up to date with security briefings.

GCHQ works alongside MI5 and the Secret Intelligence Service (MI6) to keep Britain safe. The ingenuity and problem-solving of its wartime founders is still abundant today in how its people help to counter online and real-world threats from nation states, criminal groups, terrorists, and individuals.